The comment settings are in the Discussion setup page.  This page consists on a series of check boxes where you turn features on or off. You will need to play with these by setting check marks in the appropriate boxes.  If you are allowing users to enter comments make sure you have a spam filter turned on.  (Note:  Activate the plugin “Akismet” to prevent spam. You will need to sign up for this but there is a no fee option.)  Following is two screenshots of the Discussion setup screens. (Not everything has been included. You can look at the complete setup screen yourself by clicking on Settings->Discussion.)